I changed bushings and pins last year in my passenger door.
Here are some tricks I found:
I made my own spring removal tool from some old steel, bolts, nuts, and washers. It's similar to the tool you'd buy.
Since the metal I used to compress the spring was too weak, it ended up bending til I got the spring completely out; and since it also took so long to compress the spring, I decided against using my tool to re-install the spring.
Please note: While the following methodology used to re-install the spring works, it is dangerous. Please read the posts by Rlith and Blazee below.
So, I put the spring in the vise and slowly compressed it and then using thin wire, I wrapped it along its length to keep it compressed once I removed it from the vise. I made several passes with the wire to make sure it would hold. I opened the vise, rotated the spring 180 degrees along its length, recompressed it, and wired it a second time so that the spring would be straight, not arched, for installation. Then, out to the Blazer. I probably held the spring in place with a needle nose pliers and used a wire cutter to snip one of the wires. With the 2nd wire still in place, I made sure the spring was lined up on the hinge and then cut the other wire. (I put ear muffs on cuz I had no idea how loud it would be when the spring expanded and hit the hinge - my hearing is damaged, so I don't take chances anymore.) Anyway, all that was left was to use the needle-nose pliers to pull the pieces of cut wire out of the spring. Oh yeah, I probably had safety glasses on (maybe just regular eye glasses at the very least) while compressing the spring and also when I cut the wire off it.
Since some of the wire bits were a pain to get out of the spring and because the wire I used was very strong, I decided the next time I did this I would only make one pass with each of the two wires.
Why didn't I buy a spring removal tool? Well, I guess I'm too cheap.
Instead of a socket set extension, I found a bolt laying around, maybe 1/2 inch diameter and 6" - 8" long, and ground a point on the threaded end. The pointed end fits into the small, shallow holes I drilled in each end of the new hinge pin.
The pointy bolt in the drilled pin reduced the number of times I had to re-center the bolt as I hammered the pin into place.
I drilled a hole in the other end of the pin as well, just in case I needed to remove it in the future.
I did remove the door myself, but I would recommend a second set of hands. I had the window fully opened so I could grab the frame. I put a floor jack and some wood beneath the end of the door to realign it (really bad bushings and an egg shaped hole in the hinge) and also to hold it in place.
Hope someone finds something in here useful.